Plasma processing apparatus

1. An apparatus for subjecting a target object to a plasma processing by using a plasma, comprising: an airtight process chamber; an intermediate electrode having a conductive partition which divides said process chamber into a plasma generating space and a processing space, and has an opening for allowing said plasma generating space and said processing space to communicate with each other; a potential applying mechanism electrically connected to said intermediate electrode, for applying an electric potential to said intermediate electrode; a support member arranged in said processing space, for supporting said target object in said processing space; a gas supply system for supplying a process gas into said plasma generating space; an exhaust system for exhausting and setting said process chamber at a vacuum; and an electric field generator for generating an electric field for exciting said process gas in said plasma generating space to convert said process gas into a plasma, said electric field having an electric field direction which is defined essentially by lines of electric force concentrically surrounding a center of said lines of electric force, wherein said partition consists essentially of a plurality of conductive beams extending in directions substantially perpendicular to said electric field direction.

2. The apparatus according to claim 1, wherein said conductive beams are radially arranged relative to a center of said conductive beams substantially aligning with said center of said electric field.

3. The apparatus according to claim 2, wherein some of said conductive beams are connected at said center of said conductive beams.

4. The apparatus according to claim 3, wherein said some of said conductive beams connected at said center of said conductive beams have warps to absorb thermal stress.

5. The apparatus according to claim 2, wherein said conductive beams are arranged to face each other with a gap therebetween at said center of said conductive beams.

6. The apparatus according to claim 2, wherein said center of said conductive beams substantially aligns with a center of said target object.

7. The apparatus according to claim 1, wherein said intermediate electrode further comprises a conductive outer frame supporting said partition.

8. The apparatus according to claim 1, wherein said outer frame of said intermediate electrode is attached to a conductive wall of said process chamber, and said potential applying mechanism includes a ground line electrically connected to said conductive wall of said process chamber.

9. The apparatus according to claim 1, wherein said electric field generator comprises an RF antenna facing said plasma generating space through a dielectric wall and a power supply for supplying an RF power to said RF antenna.

10. The apparatus according to claim 1, wherein said electric field generator comprises a generator for generating a microwave and a wave-guide mechanism for transmitting said microwave to said plasma generating space through a dielectric wall.

11. An apparatus for subjecting a target object to a plasma processing by using a plasma, comprising: an airtight process chamber; an intermediate electrode having a conductive partition which divides said process chamber into a plasma generating space and a processing space, and has an opening for allowing said plasma generating space and said processing space to communicate with each other; a potential applying mechanism electrically connected to said intermediate electrode, for applying an electric potential to said intermediate electrode; a support member arranged in said processing space, for supporting said target object in said processing space; a gas supply system for supplying a process gas into said plasma generating space; an exhaust system for exhausting and setting said process chamber at a vacuum; and an electric field generator for generating an electric field for exciting said process gas in said plasma generating space to convert said process gas into a plasma, said electric field generator comprising an RF antenna facing said plasma generating space through a dielectric wall and a power supply for supplying an RF power to said RF antenna, said electric field having an electric field direction which is defined essentially by lines of electric force extending substantially parallel to said target object supported by said support member, wherein said partition consists essentially of a plurality of conductive beams extending in directions substantially perpendicular to said electric field direction and parallel to said target object supported by said support member.

12. The apparatus according to claim 1, wherein said RF antenna is annular such that said lines of electric force of said electric field are formed to concentrically surround a center of said lines of electric force, and said conductive beams are radially arranged to have a center of said conductive beams substantially aligning with said center of said lines of electric force.

13. The apparatus according to claim 12, wherein some of said conductive beams are connected at said center of said conductive beams.

14. The apparatus according to claim 13, wherein said some of said conductive beams connected at said center of said conductive beams have warps to absorb thermal stress.

15. The apparatus according to claim 12, wherein said conductive beams are arranged to face each other with a gap therebetween at said center of said conductive beams.

16. The apparatus according to claim 12, wherein said center of said conductive beams substantially aligns with a center of said target object.

17. The apparatus according to claim 13, wherein said intermediate electrode further comprises a conductive outer frame supporting said partition.

18. The apparatus according to claim 17, wherein said outer frame of said intermediate electrode is attached to a conductive wall of said process chamber, and said potential applying mechanism includes a ground line electrically connected to said conductive wall of said process chamber.

19. The apparatus according to claim 11, wherein a coolant circulation passageway is formed in said conductive beams.

20. The apparatus according to claim 11, wherein said process gas is a gas for etching said target object.